Stability Margin Evaluation of Black-Box Power Distribution Systems in a Wide Load Range

Power module-based power distribution systems (PDSs) are extensively used in modern power conversion applications. However, the power modules usually do not provide internal topology circuit and modulation information, which makes it difficult to evaluate system stability by the general whitebox approaches. Alternatively, this paper proposes perturbation-based impedance ratio stability analysis steps, which offer stability evaluation over a wide load range and it does not require the circuit or modulation information. Firstly, the theoretical impedance ratio measurement circuit is explained with the stability criterion. Then, the analysis steps are introduced to show how the system stability margin over different loads can be evaluated by the 3-dimensional (3-D) fitting bode plot surface. Four typical module-based PDSs with seven completely different power converters are exemplified in the simulation for case studies. Finally, the correctness of the evaluated stability margins of the four studied PDSs in different loads are verified by the time-domain simulation waveforms, respectively.